Although the phrase fight like a girl has been used in a derogative way in the past, there may be some actual value to doing just that.
Just as they are the ferocious protectors of their young in the animal kingdom, Women may in some cases be as emotionally and physically wired for fighting as men are. Like men, women too have been naturally-gifted with the fight or flight response mechanism. When confronted or put in a potentially dangerous situation, this complex hormonal response, triggered in their bodies, secretes over thirty different stress hormones, like adrenalin and cortisol; all having a collective, widespread effect on the body. This adrenaline rush can increase your awareness, physical strength, mental acuity and speed/response time, all in order to quickly and adequately handle the perceived threat. This chemical reaction in the human body is not gender-specific. In fact, women - who tend to be more emotionally connected by nature - may even be quicker to sense, react and respond to her body's natural inclination to protect itself at all costs.
In terms of basic physicality, women also experience what could be considered benefits that relate to basic physical structure. First, the female pelvis is larger and broader than it is in men, so women tend to have an advantage in where their natural center of gravity is. They also tend to carry extra weight and place their balance in their hips, unlike men, who tend to carry their weight in their abdominal area. This type of weight distribution allows some women to naturally sit down on their punches more thoroughly and maintain a more balanced center of gravity. Dropping your center of gravity and sitting down on your punches adds leverage to its delivery. To put it a little more bluntly, a little junk in your trunk may add some pop to your punch (as long as it s just a little junk and not the entire junkyard).
Another benefit that women may have is a lack of societal pressure that they should be fighters by nature. Women aren’t necessarily expected to know how to fight. In some cases this may make women “more coachable.” They don't enter into the gym or in a coaching environment with preconceived notions that they are tough and already know how to fight. The male ego and pressure from society that they should be natural born killers already prevent some men from grasping the basic principles of boxing because they're too macho to start from scratch and to be told how to fight. They are so focused on showing how tough they are, that they skip over the proper technique and fundamentals that are needed to be an effective boxer.
Taking that one step further, it may even be safe to say that most women who walk into the gym may feel a greater need to prove themselves in the gym and in the ring. Because of this, they are then more willing to go that extra mile to show everyone that they can hang with the guys, are just as tough and just as deserving to train, box or compete. There's a certain resolve or inner strength that comes from needing to earn your peers' respect, so they tend to work harder, learn faster and not give up so quickly.
Unlike men, most women are not encouraged from an early age to develop actual strength, toughness and to develop themselves athletically, so you can't compare real physical strength when it comes to boxing, or any form of athletics for that matter. Physiologically though, by nature, even though men and women are competing on different physical levels, their abilities and capabilities are not all that different. Having said that, in terms of some slight anatomical differences, numerous intangibles and the desire/ability to learn, women may experience some small advantages.
Of course, there are no hard and fast rules that apply to all men or all women. These facts are blanket generalities in some cases, but there's still no denying that there are some women who can just plain fight. Gender aside and groin protector notwithstanding, women are making a distinct place for themselves in boxing…a place where fighting like a girl has a whole new meaning.